Noncorrosive oil compositions



and retain small quantities of water. ample, esters, ketones, alcohols, aldehydes, halogenated ornitrated compounds may be employed.

Patented Sept. 9, 1952 I UNITED; STATES PATENT NONCORROSI-VE on. COMPOSITIONS "John Harold Putman, Enfield, James Scott, West WimbledomLondon, and Denis William Ervine, vvTeddingto'n,England, assignors toStandaI-d Oil Development Company, a corporation. of De1aware No Drawi'ng. Application December 17, 1949, Serial No. 133,668. In Great Britai'n August This invention relates to. improved non-corrosive oil compositions; such asrust, preventing compositions, emulsifiablegcutting oils, textile oils,and' the like. It is particularly concerned with: compositions having superior wetting action combined with corrosion inhibiting properties and pertains more especially to compositions containing oil of lubricatinggrade combined with an alkali-metal benzoate.

Sodium benzoate has been proposed previously for use as an anti-corrosion agent for various aqueous solutions. For example, in the prior art the aqueous fluids used in heat exchanger have had sodium benzoate incorporated in them to and a suitable solubilizing agent shculdalso be incorporated. The solubilizing agents that may be used for this purpose are materials which, while being oil-soluble, enable the oil to take up For ex- Preierably, however, the solubilizing agents are oil-soluble metal petroleum sulphonates, i. e.

mahogany sulphonates, or the oil soluble Cs to C alcohols; particularly those mixed naturally occurringalcohols contained in animal fatty bodies such as wool grease or lanoline (C16 to C18) or sperm oil (C16 predominantly). Such animal fatty bodies may thus be used as solubilizers. In its. widest aspect, therefore, the invention provides an. improved oil composition, comprisingamajor proportion of an oil, preferably an oil butiri the preferred embodiment of this inven- =tion' it is formed in situ. For example, benzoic acid, which is itself soluble in oils, particularly mineral base oils oflubricating viscosity, may be dissolved in the oil and then neutralized by'the lubricating oils.

6 Claims. (01. 252-333) addition of free alkaliin the ,solubilizi-ng agent. The quantity of benzoic acid should be sufficient to' produce 0.05 to 5 of th'e benzoate in the/oil.

A feature of-the inventionis; therefore, a process for the preparation of an improvedlubricating oil. composition which comprises dissolving benzoic acid in arlubricating oil. and;.adding thereto a. solubilizing. agent containing: free alkali. It has .previously beenproposed, as in the U. S.

Patent to Lebo, 2,182,992,. to useoil solublexsulfonates and fatty material's such as degras: or lanollne in rust inhibiting oilcompositions. The lubricating oil compositionspreparedin accordance with this invention are particularly suitable for use in rust preventing compositions-based on Such compositions, suitable for inhibiting corrosion of metal surfaces, are commonly prepared by compounding lubricating oils with oil soluble metallpetroleum sulphonates and animal fatty bodies such as lanoline' or wool grease with or without petrolatum or microcrystallinewax and volatile solvents or diluents. This discovery isof particular value in relation to the provision of anti-corrosive soluble-oils, especially anti-corrosivecutting"oils. The principal function of a cutting flui'clis the removal of heat from'them'etal being cut and the tool which is-cutting it. This is necessary to avoid' drawing the temper of the tool and distorting the work piece. A cutting fluid must also, however, act'a's. a lubricant to facilitate the motion of metal chipsalongth'e tool face to" prevent the development of such high friction that welding takes place.

According, therefore, to one preferred embodiment, this invention comprises an improved rust preventing composition comprising a major proportion of a lubricating oil, 0.02 to 20%, preferably 2 to 5% l by weight, of oil-soluble metal petroleum sulphonatesor of animal fattybodies such as lanoline or wool grease. or both, and a minor proportion of, an alkali-metal. benzoate,

with or without petrolatum or microcrystalline wax and volatile solvents or diluents.

For cutting oils and textile oils, emulsifiers such as alkali or alkaline earth metal sulfonates must'be included to get sufficient solubility. or emulsification in water.

To fulfill their two-functions of removing' heat and reducing friction; cutting fluids are com monly emulsions of emulsible oilsacting as the lubricant, and water'acting as the coolant; The oil'sused are preferably mineral lubricating oils, towhich' known emulsifying agents have been 1 3 added. They should have viscosities of between 70 and 200 s. U. S. at 100 F.

Such fluids, containing from about 3 to 80 parts of, water; per part of oil, are apt to be corrosive to the metal surfaces they encounten'but according to the present invention, the incorporation of minor proportions of an alkali metal. 1

benzoate greatly reduces the tendency to cause.

preferably sodium benzoate.

'In addition to these essential ingredients, the soluble oil composition may also contain other materials commonly used in soluble oils.

For example, it is to be preferred that the soluble oil contains a stabilizer such as an alkali metal or alkaline earth metal naphthenate, preferably sodium naphthenate, or diethylene glycol or. a lower' aliphatic alcohol such as methyl,

ethyl,.isopropy1 or butyl alcohol; 0.05 to 5.0% of such stabilizer is adequate.

Anti-foaming agents such as silicone oils or vegetable waxes, particularly candelilla wax, may also be incorporated.

For certain applications where heavy duty conditions are encountered, it may be desirable to include an oiliness or extreme pressure agent. Typical agents which may be used are isopropyl oleate, tricresyl phosphate, chlorinated wax and fatty oils or sulphurized or phosphorized fatty oils.

Where transparent emulsions are desired, sodium resinates may also be added.

Fungicides such as sodium ortho phenyl phenate may also be incorporated to inhibit the growth of undesirable organisms.

V The amount of benzoate required is generally between 0.05 and 5.0% by weight of the soluble oil. It is most conveniently incorporated in the oil by forming it in situ. For example, benzoic acid may be dissolved in the lubricating oil and the necessary amount of alkali may be added to neutralize this acid together with any naphthenic, fatty or resin acids that may be present.

When sodium petroleum sulphonates are to be that has been added to the lubricating oil.

' Since this free alkali in the sulphonates would tend to cause gelling of the composition by virtue of its reactions with the other constituents, if left unneutralized, it will be seen that the addition of benzoic acid to the oil not only introduces a valuable anti-corrosive agent into the cutting oil, but also reduces its tendency to gel.

The presence of the benzoate in the cutting oil, in addition to reducing the corrosivity of the resulting emulsion, 'also improves its wetting properties, such that drops of the emulsion splashed into the machine or work-piece during machining operations tend to spread out over the metal surface into a thin protective film. V

A further valuable effect of the incorporation of the benzoate is in its effect in inhibiting corrosion of cast iron. Aqueous solutions of sodium benzoate even in 1.5% concentration are ineffective in preventing the corrosion of cast iron and sodium-petroleum sulphonates in mineral lubricating oils are not completely effective. The combination of the two, however, appears to have a synergistic effect, resulting in leaving cast iron unaffected.

When soluble oils containing alkali-metal benzoates inaccordance with the preferred embodiment of this invention are emulsified with water, it is: possible that part of the benzoate present in the oil' passes into solution in the water of the emulsion.

A further aspect of the invention is, therefore, the preparation of a soluble oil emulsion by emulsifying a composition comprising a lubricating oil having a viscosity between '70 and 200 .Saybolt Universal Seconds at F., preferably between 100 and S. U. S., and an emulsifying agent such as an oil-soluble metal petroleum sulphonate, preferably sodium petroleum sulphonate with a dilute aqueous solution of an alkalimetal benzoate, preferably sodium benzoate.

From 3 to 80 parts by volume of the aqueous solution of benzoate may be used per part of oil composition fo cutting and textile oils,.and the concentration of the benzoate solution preferably should be such that after emulsification there is present from 0.05 to 5.0% by weight of benzoate by weight of soluble oil.

In oils used merely as coatings to inhibit rusting the oil soluble sulphonates and animal :fatty bodies such as lanoline, etc., act in a dual capacity. They are known improvers for rust preventing agents and they act also, in the present case, as the solubilizing agents for the benzoate.

Furthermore, commercial petroleum suphonates which are usually available frequently contain free alkali as an impurity and when such sulphonates are compounded into rust preventing compositions with lubricating oils and lanoline, without neutralizing the alkali, a reaction between the alkali and the sulphonates andlanoline tends to cause the composition to gel on storage. Accordingly it has been necessary in the past to purify the usual commercial grade sulphonates to remove the free alkali, for use in commercially attractive compositions.

However, when such sulphonates are added to lubricating oils containing benzoic acid, the free alkali is neutralized and not only is the gelling tendency eliminated, but an effective anti-rusting and anti-corrosive agent'is simultaneously incorporated into the product.

Therefore, it will be seen that rust preventing compositions which are improved both as'to their anti-corrosion properties and in their reduced tendency to gel, may conveniently be prepared by dissolving benzoic acid in lubricating oil and .by adding alkaline oil-soluble metal petroleum sulphonates whose free alkali content is sufgeneous, but the amount required 'is not very critical and there will generally be suficient water present in the sulphonates to provide the required quantities. Any fre alkali required to beadded to the sulphonates to bring their alkaline content up to the required amount may conveniently be added as an aqueous solution of 50 concentration by weight.

The total amount of water may readily be determined by the appearance of the resulting composition.

The amount of alkali-metal benzoate required in the lubricating oil composition is small and may be, for example, between 0.05 and 5.0% by weight, preferably between 0.25 and 2.5% by weight, of the final composition. Preferably sodium benzoate is used because of its availability and low cost. The other alkali metal benzoates seem to be about equally effective, however.

The lubricating oil into which the benzoate is to be incorporated may be a hydrocarbon oil or a synthetic oil from any source, but preferably it is an oil of mineral base.

The oil-soluble petroleum sulphonates may be any alkali-metal or alkaline earth metal sulphonates, the sodium sulphonates being preferred. The quantities required vary somewhat with the intended use, but in general about 0.02 to 2% is satisfactory. The other solubilizing agents mentioned above may be used in similar proportions.

It is convenient to use a volatile solvent in the rust preventing composition to assist in applying the composition to metal surfaces, and while any of a number of conventional solvents may be used, it is desirable that the solvent chosen should not evolve toxic vapors. It should have a boiling point in the range 50 to 200 C., and in general a hydrocarbon solvent such as petroleum naphtha or white spirit is preferred.

When a wax is used in the composition, it may be any of the usual petroleum waxes from an oily paraffin wax to a hard de-oiled petrolatum. In general, where rust prevention is the primary object the hard microcrystalline wax is found to be the best because it has a better crystalline structure for coating compositions.

Other compositions conventionally added to soluble oils and rust preventives of this type may also be incorporated, for example, aliphatic alcohols, particularly those having from 3 to 12 carbon atoms in the molecule, such as isopropyl alcohol, butyl, amyl, hexyl, octyl and decyl alco- 1101, may be added to increase the mutual solubilities of the ingredients and to act as waterdisplacing agents. Amines, e. g. phenyl naphthylamines, and other known anti-oxidants may also be incorporated.

In a test of the properties of a rust preventive composition with and without the addition of sodium benzoate, 0.25% sodium benzoate increased the humidity cabinet life of a rust preventive from 12 to hours and in another test 0.5% increased the Life from 18 to 100 hours.

What is claimed is:

l. A composition consisting essentially of a mineral oil base containing about 0.05 to 5% by weight, based on the total composition, of sodium benzoate, and 0.02 to 2% of an oil soluble metal sulfonate v 2. An oil composition comprising a major proportion of a mineral base oil, 0.05% to 5% by weight, based on the total composition, of sodium benzoate, and 0.02 to 20% of an oil soluble alkali metal petroleum sulfonate.

3. An emulsiflable oil composition comprising a major proportion of a mineral base oil, 0.25 to 2.5% by weight of sodium benzoate, and 2 to 5% of oil soluble petroleum suli'onate.

A non-corrosive oil composition comprising mineral oil of lubricating viscosity, 0.05 to 5% by weight, based on the total composition, of sodium benzoate, a solubilizer comprising 0.02 to 20% of oil soluble metal petroleum sulfonate, and about 0.05 to 5% of a stabilizer.

5. Composition according to claim 4 wherein the stabilizer is a metal naphthenate.

6. Composition according to claim 4 wherein the stabilizer is a C1 to C4 aliphatic alcohol.

JOHN HAROLD PUTMAN.

JAMES SCOTT.

DENIS WILLIAM ERVINE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,487,081 Swenson Nov. 8,, 1949 2,504,200 Johansson Apr. 18, 1950 FOREIGN PATENTS Number Country Date 410,323 Great Britain May 17,, 1934 588,565 Great Britain May 28, 1947 

4. A NON-CORROSIVE OIL COMPOSITION COMPRISING MINERAL OIL OF LUBRICATING VISCOSITY, 0.05 TO 5% BY WEIGHT, BASED ON THE TOTAL COMPOSITION, OF SODIUM BENZOATE, A SOLUBILIZER COMPRISING 0.02 TO 20% OF OIL SOLUBLE METAL PETROLEUM SULFONATE, AND ABOUT 0.05 TO 5% OF A STABILIZER. 